Steel roll



plication, filed under -nre checks or cracks formed UNITED STATES "i ATi-:Nr,osfsics A I C frmm- WM 1-.. f

No Drawing.

Application December a. 194i; Serial No. 422.000

some.(cast-tiff I a stage at which ordinarily a cast roll would be The invention pertains to an improvement in steel rolls for use particularly in a hot mill and in the process of forming various types of metallic plates-or shapes. I l

The-subject matter of" this application ls re-- lated to thesubject matter of my co-pending ap- Serial No. 422,010.

One of the objects of the invention ls to pro vide a roll of alloy steel having great strength and a shock resisting qualities capable of withstanding the heavy loads and stresses'to lected in service.

Another object of'the invention is to provide a which it is subroll formed of alloysteel for use in a' hot mill and being particularly suitable for such use in that its construction is such as to avoid having enga ing surface. y v

A further object of the invention is the provision of a steel roll having a surface hardness and hardness of the metal adjacent the center of the roll differ only in a minute degree so that,

by reason of this substantially constant hardness throughout the entire mass of the roll, the latter may, due to wear which takes place in service,

be machined to present a roll of rslightly less diameter than its original configuration but, at the same time, sacrifice none of its original charaoteristics.

Heretofore rolls. for use in a hot mill have been made of cast steel or steel alloys in attempts to provide a dense, ductile, hard and toughroll of sufiicient, strength and toughness to withstand the shocks and blows to which the same are subiected and, at the same time. to limit the magnitude of thefire checks or cracks formed in the roll surface by reason of the particularuse to ally not proved successful because if the roll surface is formed extremely hard, it has also generally been brittle and it is found where the surface of the roll is softer and more ductile to prevent fire checks, the wearing quality of the roll has suffered.

I have found that by combiningsaid hereinon its outer metal even date and bearing contactingthe hot met and then advanced away'from the hot metal to be t rendered useless, the roll of the present invention may be further machined or dressed to extend materially the life of the roll. Further it has been found that in cast rolls where the 'roll surface is hard. it is consequently brittle and develops lire cracks orchecks therein. These fire cracks or checks produce in the formation or fabrication of metal, markaehibossments, or raised portions oorrespondin' to the fire cracks which persist throughout 1 the rolling and working stages of the metal acted upon by the 1 rolls. The fire checks, as will be understood during the process of rolling hot metal. are accentuated or magnified due to the portion of the roll being extremely heated subjected to a cooling medium or agent which consequently sets up w roll structure and incr ases the size of the fire checks.

Theroll of the'present invention is capable of rapid change of heat without rupturing the surface by the'formation offire cracks or checks and, while it will be understood that the absolute elimination of fire cracksis not thought possible,

the checks formed in the surface of the roll embodying the present invention are of such minute which it is placed. -'Ihese attempts have generdimensions as: to be microscopic and, therefore, of no consequence since, in practice, it has been found that they leave no counterpart impression upon the metal being worked, and do not grow or enlarge as a result of the wide range of temperature to which the roll is subjected in service.

I" find in practice that these undesired effects in the roll can be substantiallyeliminated-and the production of a-tough, durable and exceptionally strong roll may be produced by first employing an amount of carbon considerably less than that required to form cast iron and introducing a sufiicient amount of copper with a related proportion of molybdenum. A hardening agent in the-form of manganese is also pressproduct.

cut with a slight percentage of sulphur and 'phosphorus to reduce the brittleness of the finished It is to be noted that copper does not oxidize and, upon using in the charge, scrap rolls made previously from the herein contained combination of elements and which have, due to the usage and continued machining, been rendered unfit for further service, a slight amount ofcopper need be added. to the charge'to bringit within the hereinafter set' forth proportion of this element.

at internal stresses in the In carrying out the invention, I preferably employ the hereinafter set forth proportions or ranges of the above-mentioned elements,

It has been found. in practice that the most desired results are obtained in the rolls by the following method of treatment or processing of a roll after it has been formed to enhance greatly the physical properties of the steel roll. Being processed by the following method, the roll" formed by the above-mentioned elements has Shore hardness of from 35 to 40 as well ashaving a high elastic ratio and great strength while, at the same time, easily machined. The preferred method-of treating the roll is first to normalize the metal thereof by subjecting the roll to a heat treatment of between 1600 to 1700 F., and then allowing'it to cool. The roll aaaazee Other changes in the percentages than the one hereinabove set forth may, oi course, be made without departing from within the spirit of the invention and the scope of the appended claims.

' .I claim:

1. A steel roll for hot metal rolling mills, said Per cent Carbon c30to .60 Manganese. .60 to 1.25 Silicon .30 to .60 Sulphur and phosphorus a maximum 0! .06 Copper .50 to 2.00 Molybden .20to .60

1.25% manganese, .60% silicon, .06% sulphur and phosphorus, 2.00% copper, and .60% molybdenum.

2. A steel roll for hot metal rolling mills, said roll comprising not more than .60% carbon, .06% sulphur and phosphorus together with approximately .60% to 1.25% manganese, .30% to .60% silicon, approximately 2.00% copper and 20% to .60% molybdenum. g

3. A steel roll for hot metal'rolling mills comprising an alloy'containing '.30% to .60% carbon, .60% to 1.25% manganese, to .60% silicon, .06% maximum of sulphur and phosphorus, approximately 2.00% copper, and 20%. to .60%

,molybdenum.

4. A steel roll adapted tohot metal rolling mill, said roll comprising an alloy containing a maximum of .60% carbon, 06% or equal portions of sulphur and phosphorus, about .60% to 1.25% manganese, about .30% to .60% silicon, about approximately 2.00% copper, and about .20% to .60% molybdenum.

wms'onn c. 

